Field of the Invention
The present invention relates to an engine system having a coolant control valve unit that can control each of coolant that is distributed to a radiator, a heater, and an oil cooler to improve entire cooling efficiency and that can effectively remove a bubble that is included in coolant and that can improve high temperature stability of a coolant control.
Description of Related Art
An engine generates a torque by combustion of fuel and discharges the remaining energy as heat energy. Particularly, while circulating the engine, a heater, and a radiator, coolant absorbs heat energy and discharges the heat energy to the outside.
When a coolant temperature of the engine is low, viscosity of oil increases and thus a frictional force thereof increases and fuel consumption may increase and a temperature of an exhaust gas slowly rises, whereby an activation time of a catalyst may be extended and a quality of an exhaust gas may be deteriorated. Further, as a normalization time of a heater function is extended, an occupant and a driver may be cold.
When a coolant temperature of the engine is excessively high, knocking occurs, and in order to suppress knocking, when adjusting ignition timing, a performance thereof may be deteriorated. Further, when a lubricant temperature is excessively high, a lubrication operation may be deteriorated.
Therefore, one coolant control valve that controls several cooling elements through one valve is applied with a method of highly maintaining a coolant temperature of a specific portion of an engine and low maintaining a coolant temperature of other portions thereof.
A system that circulates coolant with a high pressure instead of opening coolant to the outside is applied, and as a cooling system becomes complex, a structure and method for effectively removing a bubble that is formed therein are required.
Further, in a condition in which coolant of the engine is in a high temperature, if a coolant control valve does not operate by valve fixation, by enabling a safety valve to operate by a coolant temperature, a research that bypasses coolant to the radiator side has been performed.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.